The present invention is related to a method for the earthwork of a foundation sunk for a wind energy facility.
In principle, two variants are possible for the anchoring of the pipe tower of a wind energy facility. In the first variant, a pipe piece with a circulating flange is set in concrete into a foundation. The tower foot of the wind energy facility is subsequently screwed with the pipe piece. In the second variant, not a pipe piece but an anchor cage, consisting of several anchoring bolts, is set in concrete in the foundation sunk. The tower foot is then screwed together with the anchoring bolts.
In the last mentioned variant, the anchoring bolts are integrated into an anchor cage. The anchor cage has an anchor plate or an anchor ring on its ground, which is screwed together with the anchoring bolts. The free end of the anchoring bolts protrudes from the foundation sunk, in order to be screwed together with the tower foot flange.
In the part of construction work, the production of the foundation sunk takes place by securing the free ends of the anchoring bolts with a reusable anchoring bolt strickle board. Every time, the anchoring bolt strickle board consists of two half-circles, which are connected with each other through link plates on the perimeter. The half circles have bores at predefined positions for the accommodation of the anchoring bolts. In order to fix the anchoring bolt strickle board, the same is secured on each anchoring bolt through a pair of nuts. Subsequently, the foundation reinforcement is laid through the anchor cage, the foundation sunk and its reinforcement being significantly greater than the anchor cage in this. For example, the foundation sunk may have dimensions of about 15×15 m, whereas the anchor cage has a diameter of 3 to 5 m for example, depending on the size of the pipe tower. After placing the reinforcement and a corresponding planking of the foundation sunk, the latter is poured with concrete. After the pouring, the nut pairs are relieved from the anchoring bolts and the anchoring bolt strickle board is removed. Subsequently, a load distribution plate made in one piece or plural pieces is set on the anchoring bolts and is horizontally oriented on the anchoring bolts, via filling plates and adjustment screws. The oriented load supporting plate is subsequently under-poured with a high-strength swelling mortar. The under-poured load supporting plate forms the support area for a tower foot flange. In the fastening of the tower foot flange, the anchoring bolts are tensioned across the foundation sunk.
It has proven to be disadvantageous in the procedure for the earthwork mentioned above that mounting and dismounting of the anchoring bolt strickle board is an expensive operation. Additionally, inaccuracies in the bores of an anchoring bolt strickle board are created through the reuse thereof, which are maintained when the reinforcement is placed and in the subsequent pouring of concrete, and thus lead to inaccuracies of the anchoring bolt circle.
The present invention is based on the objective to provide a method for the earthwork of a foundation sunk and for the preparation of the installation of the tower, which can be realised with simple means in the part of construction work.